Wave Propagation in Biaxial Planar Waveguides using Equivalent Circuit in

By applying Laplace transformations to Maxwell's equations, transmission line equations are derived for guided wave propagation in planar waveguides. For the first time an intuitive equivalent T-circuit model is derived for inhomogeneous planar waveguides of materials having biaxial dielectric permittivity tensor, which may have conductivity, and attenuation along the propagation direction. The materials may also have arbitrary refractive index profile along any of the three axes. TE and TM mode equivalent circuits for dielectric layers are derived and the mode propagation constants are calculated from the resonances of the cascade of the elementary T-circuits. The method can be extended, so as complete waveguide characterisation would be possible, allowing dispersion, cut-off frequencies and mode field plots to be calculated incorporating the influence of material conductivity and attenuation